Basic Study On Small Yardstick And Shallow TEM Measurement Method And Device

Bioelectric impedance tomography is a non-invasive detecting technology which extracts biomedical information by measuring human body's electrical characters (conductive, impedance and permittivity). This technology has many advantages such as non-invasive, real-time measurement and it has bright future. Electrical Impedance Tomography (EIT) and Magnetic Induction Tomography (MIT) are two representative technologies of bioelectric impedance tomography.Biology is a complicated system and its character information should be obtained in many ways. EIT and MIT excite tissue by using stable, single frequency current and magnetic field then the electromagnetic response can be measured. In this paper, transient electromagnetic method (TEM) in the geology prospecting is used for reference, small yardstick and shallow TEM is put forward to measure biology tissues. That is DC current is injected into excitation coil, so static state magnetic field is strike up, this field is called the first field, then the DC current is cut off quickly, after that eddy current will be induced in the dielectric, different conductivities distribution correspond to different eddy current field decay process, electricity characteristic structure can be confirmed by measuring and analyzing magnetic field response in the half space. Transient electromagnetic excitation signal is a multi-frequency signal, this is different from single and static frequency excitation which is used in EIT and MIT.In this paper, the induction eddy current decay process in the conducting material is analyzed and computed at first(the dielectric is excited by transient magnetic field),then the eddy current density distribution in the conducting material is simulated, the simulation result indicates that TEM could distinguish objects interface of different conductivities very well. Next, the design and functions of experiment circuit are discussed particularly, some agar models of different conductivities are measured by using this circuit, some useful conclusions are received. At last, some amelioration advices are given to overcome shortages in the research process.